The BiVO.sub.4 microspheres and Sm.sup.3+-doped BiVO.sub.4 polygons were prepared via a facile hydrothermal method by means of K.sub.6V.sub.10O.sub.28·9H.sub.2O as a novel vanadium source. Optimized ...temperature and pH value of prepared BiVO.sub.4 were obtained. The polycrystalline BiVO.sub.4 microspheres prepared at T = 140 °C, pH 4, demonstrates the best photocatalytic activities for degrading dyes under UV radiation. This is resulted due to transfers of photogenerated electrons from tetragonal to monoclinic phases. In contrast to the undoped BiVO.sub.4, the photocatalytic activity of Sm.sup.3+-doped BiVO.sub.4 polygons is drastically enhanced not only under UV radiation but also under visible light radiation. The optimized Sm content was found to be 10 %. Enhanced efficiency with the doped sample is attributed to the dopants' role in blocking recombination of photogenerated electron-hole pairs. This work offers a simple route to obtain mixed phase BiVO.sub.4 and provide an effective way to achieve higher photocatalytic activity by doping the Sm.sup.3+ in the semiconductor catalysts.
Low molecular weight and high molecular weight metal ion binders present in blood plasma are shortly described. The binding of vanadium and ruthenium complexes by these components has received much ...attention, namely their interactions with human serum albumin and transferrin, and these studies are critically reviewed. The influence of the protein binding on the bioavailability of the prospective drugs, namely on the transport by blood plasma and uptake by cells is also discussed. It is concluded that vanadium compounds are mainly transported in blood by transferrin, but that no study has properly addressed the influence of albumin and transferrin in the vanadium uptake by cells. Ruthenium complexes bind strongly to HSA, most likely at the level of His residues, leading to the formation of stable adducts. If the kinetics of binding to this protein is fast enough, probably they are mainly transported by this serum protein. Nevertheless, at least for a few Ru(III)-complexes, hTf seems to play an active role in the uptake of ruthenium, while HSA may provide selectivity and higher activity for the compounds due to an enhanced permeability effect.
The emerging electrochemical energy storage systems beyond Li‐ion batteries, including Na/K/Mg/Ca/Zn/Al‐ion batteries, attract extensive interest as the development of Li‐ion batteries is seriously ...hindered by the scarce lithium resources. During the past years, large amounts of studies have focused on the investigation of various electrode materials toward emerging metal‐ion batteries to realize high energy density, high power density, and a long cycle life. In particular, vanadium‐based nanomaterials have received great attention. Vanadium‐based compounds have a big family with different structures, chemical compositions, and electrochemical properties, which provide huge possibilities for the development of emerging electrochemical energy storage. In this review, a comprehensive overview of the recent progresses of promising vanadium‐based nanomaterials for emerging metal‐ion batteries is presented. The vanadium‐based materials are classified into four groups: vanadium oxides, vanadates, vanadium phosphates, and oxygen‐free vanadium‐based compounds. The structures, electrochemical properties, and modification strategies are discussed. The structure–performance relationships and charge storage mechanisms are focused on. Finally, the perspectives about future directions of vanadium‐based nanomaterials for emerging energy storage devices are proposed. This review will provide comprehensive knowledge of vanadium‐based nanomaterials and shed light on their potential applications in emerging energy storage.
The vanadium‐based materials family has a lot of promising electrodes with different compositions, structures, and properties for emerging electrochemical energy storage systems. Recent investigations on vanadium‐based nanomaterials for emerging metal‐ion batteries beyond lithium demonstrate considerable interesting and exciting results. These important progresses are comprehensively reviewed with fundamentals, mechanisms, and future opportunities discussed.
•Electrical energy storage with Vanadium redox flow battery (VRFB) is discussed.•Design considerations of VRFBs are addressed.•Limitations of each component and what has been/is being done to address ...said limitations are discussed.•Critical research areas along with future development recommendations are highlighted.
Interest in the advancement of energy storage methods have risen as energy production trends toward renewable energy sources. Vanadium redox flow batteries (VRFB) are one of the emerging energy storage techniques being developed with the purpose of effectively storing renewable energy. There are currently a limited number of papers published addressing the design considerations of the VRFB, the limitations of each component and what has been/is being done to address said limitations. This review briefly discusses the current need and state of renewable energy production, the fundamental principles behind the VRFB, how it works and the technology restraints. The working principles of each component are highlighted and what design aspects/cues are to be considered when building a VRFB. The limiting determinants of some components are investigated along with the past/current research to address these limitations. Finally, critical research areas are highlighted along with future development recommendations.
En la producción de ácido sulfúrico por el método de contacto se utilizan catalizadores de pentóxido de vanadio, los cuales, una vez agotados, se almacenan por tiempo indefinido de acuerdo con ...regulaciones medio ambientales. En el presente trabajo se evalúa la recuperación de elementos metálicos contenidos en estos catalizadores, mediante lixiviación con ácido sulfúrico al 15 % v/v y posterior precipitación con solución amoniacal al 25 % m/m. A partir de un balance de masa se definieron las masas y composición química teórica del producto recuperado y de los residuales líquidos y sólidos. El procesamiento permitió obtener 1,756 g de concentrado (14,9 % del residual), formado mayormente por V.sub.2O.sub.5; Fe.sub.2O.sub.3; MnO, además Cr.sub.2O.sub.3, NiO, CaO, CoO y CuO. Los elementos metálicos se determinaron por espectrometría de absorción atómica, con excepción del vanadio, que se comprobó mediante espectroscopia ultravioleta visible y fluorescencia de rayos-X. Esta evaluación constituye una alternativa para obtener óxidos metálicos a partir de residuos sólidos contaminantes, a la vez que contribuye a la protección del medio ambiente. Palabras clave: catalizadores agotados; producción de ácido sulfúrico; lixiviación ácida; recuperación de vanadio. For producing sulfuric acid by the contact method, vanadium pentoxide catalysts are used, which are stored indefinitely in accordance with environmental regulations once exhausted. The present work evaluates the recovery of metallic elements contained in these catalysts by leaching with sulfuric acid at 15% v/v and subsequent precipitation with 25% ammoniacal solution m m. A mass balance was used for determining theoretical chemical composition and the masses of recovered product and the liquid and solid residuals. The processing allowed to obtain 1.756 g of concentrate (14.9% of the residual) formed mainly by V.sub.2O.sub.5; Fe.sub.2O.sub.3; MnO, in addition Cr.sub.2O.sub.3, NiO, CaO, CoO and CuO. The metallic elements were determined by atomic absorption spectrometry, with the exception of vanadium, which was determined by visible ultraviolet spectroscopy and X-ray fluorescence. This result constitutes an alternative to obtain metallic oxides from solid waste contaminants while contributing to preserve the environment. Keywords: depleted catalysts; production of sulfuric acid; acid leaching; recovery of vanadium.
Vanadium is special in at least two respects: on the one hand, the tetrahedral anion vanadate(
v
) is similar to the phosphate anion; vanadate can thus interact with various physiological substrates ...that are otherwise functionalized by phosphate. On the other hand, the transition metal vanadium can easily expand its sphere beyond tetrahedral coordination, and switch between the oxidation states +
v
, +
iv
and +
iii
in a physiological environment. The similarity between vanadate and phosphate may account for the antidiabetic potential of vanadium compounds with carrier ligands such as maltolate and picolinate, and also for vanadium's mediation in cardiovascular and neuronal defects. Other potential medicinal applications of more complex vanadium coordination compounds, for example in the treatment of parasitic tropical diseases, may also be rooted in the specific properties of the ligand sphere. The ease of the change in the oxidation state of vanadium is employed by prokarya (bacteria and cyanobacteria) as well as by eukarya (algae and fungi) in respiratory and enzymatic functions. Macroalgae (seaweeds), fungi, lichens and
Streptomyces
bacteria have available haloperoxidases, and hence enzymes that enable the 2-electron oxidation of halide X
−
with peroxide, catalyzed by a Lewis-acidic V
V
center. The X
+
species thus formed can be employed to oxidatively halogenate organic substrates, a fact with implications also for the chemical processes in the atmosphere. Vanadium-dependent nitrogenases in bacteria (
Azotobacter
) and cyanobacteria (
Anabaena
) convert N
2
+ H
+
to NH
4
+
+ H
2
, but are also receptive for alternative substrates such as CO and C
2
H
2
. Among the enigmas to be solved with respect to the utilization of vanadium in nature is the accumulation of V
III
by some sea squirts and fan worms, as well as the purport of the nonoxido V
IV
compound amavadin in the fly agaric.
Biological functions of vanadium are based on both the vanadate-phosphate analogy and interactions of the oxidovanadium moiety with proteins.
There is increasing interest in vanadium redox flow batteries (VRFBs) for large scale-energy storage systems. Vanadium electrolytes which function as both the electrolyte and active material are ...highly important in terms of cost and performance. Although vanadium electrolyte technologies have notably evolved during the last few decades, they should be improved further towards higher vanadium solubility, stability and electrochemical performance for the design of energy-dense, reliable and cost-effective VRFBs. This timely review summarizes the vanadium electrolyte technologies including their synthesis, electrochemical performances, thermal stabilities, and spectroscopic characterizations and highlights the current issues in VRFB electrolyte development. The challenges that must be confronted to further develop vanadium electrolytes may stimulate more researchers to push them forward.
A series of iron-vanadium mixed oxide catalysts prepared by the coprecipitation method were used for the selective catalytic reduction NO with NH.sub.3. The activity evaluation results exhibited that ...the activity of Fe.sub.2O.sub.3 was enhanced by addition of a little V, and the Fe-V-O.sub.x catalyst also showed high resistant to the SO.sub.2 and H.sub.2O poisoning in the tested condition. The XRD, NH.sub.3-TPD, H.sub.2-TPR and in situ DRIFTS characterization results displayed that the lower grain size of Fe.sub.2O.sub.3, the reinforced acidity and high redox ability should be the critical factors for the Fe-V-O.sub.x catalyst to achieve the high NH.sub.3-SCR performance. Graphical
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